- The buried position of the tape shouldextend to whole cable line and be about 50 cm over the cable and be about 50 cm outside both outer edge cables.

-The tape should be made of anti corrosion material such as a vinyl, and bestriking colors to the color of the soil.

-The voltage, the name of the cable lineand the management unitshould be described on the caution tape at intervals of about 2 m.

- The steps needlework type of the caution tape should be used so that the tapeis not cut when pulled by heavy civil machine.

Danger: High voltage cable

Cable 110kV Thành Công – Giám

Power company Đống Đa

Figure 416 Example of the caution tape

Article 417. Cable installation in chemical erosion soil

The vinyl and the polyethylene with the following characteristics are generally preferableasthe material of the protective covering outer sheath to protect the cable from corrosion.

1.High insulation and a high dielectric strength are possessed and they do not decrease over a long time.

2.The waterproof, the oil-proof, chemical resistance and the flame resistance are possessed, and a chemical characteristic is stable over a long time.

3.Excellent weather resistance and resistance to aging are possessed.

4.Abnormality is not appeared in temperature of the outer sheath of the cable operated generally (About -10 deg C to 70 deg C).

5.Mechanically strong, excellent flexuous and abrasion resistance are possessed, and friction coefficient is not large.

6.The manufacturer can process easily.

Article 418. Compliance with cable installing route

In case that it is impossible to construct the cable line in designed route as other equipment of laying underground (pipeline and water service, etc.) exists or the owner of the construction land does not approve, the change in the route should be examined by conferring with the design unit.

Section 3 REQUIRED DIMENSIONS FOR INSTALLATION

Article 419. Depth of buried cable

Refer to Chapter 3-2-4 in Technical RegulationVol.1.

Article 420. Parallel cables

Refer to Chapter 3-2-4 in Technical RegulationVol.1.

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Article 421. Clearance trees

When the cable isarranged through the forest or area where trees are planted, the distance from the cable to the root of a treeshould be secured 2 m or more. If local concerned parties agree the arrangement and the cable is inserted in the protective pipe, the distance is permitted to be shortened.

In the garden with small trees, the distance is permitted to be shortened up to 0.75m.

Article 422. Special cases

In case that the metal sheath of the cable may be corrodedwith the straying current fromelectric railways, a cable should be installedin the insulation cable blockto prevent from corrosion.In addition, anti-corrosion by the protective covering outer sheath such as vinyl is also effective.

Article 423. Cable corridor

Refer to Chapter 3-2-4 in Technical RegulationVol.1.

Article 424. Crossing each other

Refer to Chapter 3-2-4 in Technical RegulationVol.1.

Article 425. Prohibition of installing cables in the same vertical plane

When the cable is laid directlyon the top and bottom ofother pipe such as gas pipe or heat pipe, the following fears may occur, so the cable should be inserted in the pipe to defend from them.

-The earth load concentrates on the cable.

-The adverse effect (heat, gas, and polluted material, etc.) that leaks from other pipe is received to the cable.

- When other pipe is constructed, the damage by the heavy civil machine for digging is received to the cable.

Section 4 CABLE INSTALLATION INSIDE CULVERT, CANAL AND

PRODUCTION AREA

Article 426. General

Since the cablein the culvert or cable canal etcis. protected fundamentally, theadditional cover should not be attached because it makes cable temperature rise. However, the additional cover should be used in consideration of a thermal influencewhen it is used to preventhe outer sheath from corrosion by the polluted material.

Article 427. Clearance between cable shelves

When the interval of the cable support part is short, the cable is rarely damaged by reducing the stress by the weight. When it is long,the snaking installation conducts easily and the change of the cable tension is decreased according to the expansion or contraction by heat.

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The interval of the cable support part should bemade as the design specification because of the above-mentioned reasons.

Article 428. Soft pad for cables

The cable without metal cover should be fixed by the soft pad to prevent the metal part of the support shelf to damaging the insulator.

-Condition of the soft pad

Soft pad does not make protective covering outer sheath changed by vicious chemical materials.

The rust of the metalpart of the cable and the support shelf is notdeveloped. (It does not become a damp or wet condition.)

Article 429. Cables go along the wall

When the cable with the leadsheathedand the cable without the metal cover are installed along the concrete and the brick wall, thecable should be installed by making space between thecable and the wall to avoid the corrosion by rain water and the scratch by rubbing to the wall.

Article 430. Cables installation inside foundation

Article 431. Cables on wooden floor

The offset distance from thecable to the surface of wooden floor should be secured 50mm or more because the danger such as a fire and the electric shock may occur.In addition, the cable in the wooden ceiling should be installed in a cable block or a nonflammable box.

Article 432. Cables go through wall

The conditions that the cable is permitted to be thrust through andbe installed at wooden floor and wall are as the following.

-The distance of both sides of projection from the floor or the wall of cable block should be secured 50mm or more.

-The nonflammable material should be filled between the cable block and the cable. As exceptional case, it is permissible that the nonflammable material is not filled between the cable block and the cable when the distance of projection is 100mm or more and the distance from the cable to the wall is 50mm or more.

Article 433. Cable installation inside cable canal

It is preferable that the cable is arranged on the cable rack as much as possible to avoid the damage by the movement due to heat expansion and contraction, the corrosion due to underground waterand water trees aging.

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The rule of arrangement on a cable rack is as follows.

1.When there are cable racks in both sides of the cable tunnel or the cable canal, the control cable and the power cable with voltage up to 1 kV should be arranged on one side, and the other side should be secured for the power cable with voltage exceeding 1kV.

2.When there is a cable rack on one side of the trench, cable, control cables and power cable lines with voltage up to 1 kV should be arranged at the bottom but above power cable lines with voltage exceeding 1 kV on the same side.

3.The cables should be arranged on two different racks, which are operating or reserved cables used for the generator and transformer with voltage exceeding 1 kV and its for consumer class 1.

Article 434. Cables installed on the cable canal

Power cable lines installed on the cable canals should comply with requirement in 7articlein Guideline Vol.1.

Article 435. Prohibition of sand used as covering cables

The cables (Including the control cable) in the cable canal should not be covered with sand, since a lot of types of cables might be divided in the cable canal, and it is difficult to distinguish the cables.

However, it is allowed to cover with sand for the defense from the explosion.

Article 436. Requirement of installation cables

It is allowable to arrange the power cable with voltage up to 1 kVand the control cable as the way of Figure 438. However, the arrangement of the power cablewith voltage exceeding 1kV and the offset distance between thepower cable with voltage up to 1kV andthe control cable should be in accordance with Article 434.

Cable rack

Up to 1kV cable

Figure 436 Example of Arrangement of power cable and control cable

Article 437. Cable installation structure

Each size of cable installation structures should be more than the numerical value in Article 434.

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